Absorption of pentachlorophenol (PCP) by bark chips and its role in microbial PCP degradation

A pentachlorophenol (PCP)-degrading mixed bacterial population was enriched in a biofilter filled with soft wood bark chips. We found that bark chips were essential for the degradation to proceed at PCP concentrations higher than 10M. PCP-degrading bacteria were found to be extremely sensitive to PCP. Bark chips absorbed PCP reversibly, thus detoxifying the medium and allowing degradation to proceed at higher concentrations of PCP (beyond 200M).     

Isolation and characterization of novel Serratia marcescens (AY927692) for pentachlorophenol degradation from pulp and paper mill waste

Seven aerobic bacterial strains were isolated from pulp paper mill waste and screened for pentachlorophenol (PCP) tolerance on PCP containing mineral salt agar medium (MSM). The organism was characterized by 16S rDNA sequencing which showed 99.7% sequence similarity with Serratia marcescens. PCP degradation was routinely monitored with spectrophotometric analysis and further confirmed by HPLC analysis. Among seven strains, ITRC S₇ was found to degrade up to 90.33% of 1.127 mM (300 mg/l) of PCP and simultaneous release of chloride ion (2.435 mM) emphasized the bacterial dechlorination in the medium in presence of glucose as an additional carbon and energy source under optimized condition within 168 h incubation. In absence of glucose bacterium was unable to utilize PCP indicating the phenomenon of co-metabolism. Bacterium was identified as S. marcescens (AY927692), was a novel and potential aerobic bacterial strain capable of degrading PCP in axenic condition. Further, this strain may be used for bioremediation of PCP containing pulp paper mill waste in the environment.     

Comparative study of soil bacterial flora as influenced by the application of a pesticide,pentachlorophenol (PCP)

Summary The effects of pentachlorophenol (PCP) applications on the taxonomic composition of bacterial microflora were studied in water-logged soil (WS) and in shake cultures of suspended soil (SS). PCP applications resulted in a predominancy of Gram-negative bacteria over Gram-positive species. Members of theAcinetobacter group were the most common in PCP-treated soil although a small portion of the flora were in thePseudomonas-Alcaligenes group or belonged to theEnterobacteriaceae. Coryneform bacteria and species of theBacillus were the dominant forms in untreated WS; however, WS cultures treated with PCP at recommended rates (2.67 gm/m²) evidenced species ofPseudomonas, Alcaligenes, Acinetobacter, and members of theEnterobacteriaceae as the predominant bacterial species. The dominance of Gram-negative bacteria in PCP-treated soil was evidenced for 3 months after application of the compound but was not evident after 17 months when PCP had dissipated. Gram-negative bacteria found in PCP-treated soil were highly tolerant of the phenol. In WS cultures coryneform bacteria were the most common although PCP tolerance was heterogenous in nature.     

Evolution of Bacterial Diversity during Enrichment of PCP-Degrading Activated Soils

The microbiota of completely mixed soil slurry was acclimated with pentachlorophenol (PCP) or with a wood preservative mixture (WPM) containing several pollutants such as PCP and petroleum hydrocarbons. The impact of these compounds on the bacterial diversity was studied by using molecular tools. PCR amplifications of the 16S ribosomal RNA gene sequences (rDNA) were carried out with total DNA extracted from soil slurry samples taken at different time points during the enrichment process of the PCP and WPM reactors. The composition of these PCR products, reflecting the bacterial diversity, was monitored by the single-strand-conformation polymorphism (SSCP) method. Our results showed that the complexity of the SSCP profiles in the PCP reactor decreased significantly during the enrichment process, whereas they remained complex in the WPM reactor. PCR-amplified 16 rDNA libraries were generated from each reactor. The SSCP method was used to rapidly screen several clones of these libraries to find specific single-strand DNA migration profiles. In the PCP-activated soil, 96% of examined clones had the same SSCP profile, and sequences of representative clones were related to the genusSphingomonas, suggesting that the enrichment with PCP resulted in a selection of little phylogenetic diversity. Four different SSCP profiles were observed with the 68 examined clones from the WPM reactor. Representative clones of these profiles were related to Methylocystaceae or Rhizobiaceae, to sulfur-oxidizing symbionts, to the genusAcinetobacter, and to the genusSphingomonas. We also cloned and sequenced PCR-amplified DNA related to thepcpB gene, coding for theSphingomonas PCP-4-monooxygenase and detected in both reactors after two weeks of enrichment. Of the 16 examined clones, deduced amino acid sequences of 13 clones were highly related to theSphingomonas sp. strain UG30pcpB. The three remainingpcpB clones were not closely related to the three knownSphingomonas pcpB.     

The apical/basal-polarity determinant Scribble cooperates with the PCP core factor Stbm/Vang and functions as one of its effectors

Most tissues display several features of cellular polarization. Besides the ubiquitous epithelial polarization in the Apical–Basal (A/B) axis, many epithelia (and associated organs) display a Planar Cell Polarization (PCP). Recently, a crosstalk between the PCP and A/B polarity determinants has been suggested, i.e. the activity or stability of the PCP factor Frizzled is regulated by the A/B determinants aPKC and Bazooka in the Drosophila eye. We have systematically investigated genetic and physical interactions between the Drosophila A/B factors and the core PCP component Strabismus (Stbm)/Van Gogh (Vang). The A/B determinant Scribble was found to interact both genetically and physically with Stbm/Vang. We demonstrate that Scribble binds Stbm/Vang through its PDZ domain 3 and that it cooperates with Stbm/Vang in PCP establishment. Our data indicate that Scribble, in addition to its role in A/B polarity, has a distinct requirement in PCP establishment in the Drosophila eye and wing. We define a scribble allele that is largely PCP specific. Our data show that Scribble is part of the Stbm/Vang PCP complex and further suggest that it might act as an effector of Stbm/Vang during PCP establishment.     

Enhanced Remediation of Pentachlorophenol (PCP)-Contaminated Groundwater by Bioaugmentation with Known PCP-Degrading Bacteria

The objective of this study was to test whether bioaugmentation with known pentachlorophenol (PCP)-degrading bacteria (Sphingobium chlorophenolicum and Burkholderia cepacia) could enhance remediation of PCP-contaminated groundwater. Groundwater PCP concentrations were determined by US Environmental Protection Agency (EPA) method 3510C and gas chromatography. Gene expression for PCP-degrading enzymes: pentachlorophenol 4-monooxygenase (pcpB; S. chlorophenolicum) and chlorophenol 4-monooxygenase (TftD; B. cepacia) was determined by real-time polymerase chain reaction (RT-PCR) using gene-specific primers. Bioaugmented treatments with S. chlorophenolicum and B. cepacia showed 32% and 49% decrease (p < .05) whereas un-bioaugmented (indigenous) treatment did not show significant decrease (p > .05) in average PCP concentration, respectively, over 72 days. Decreased PCP levels correlated strongly (r = ?.82, p < .05) with increased PCP-tolerant bacteria in bioaugmented treatments, whereas no significant correlation was observed (r = ?.22, p > .05) in un-bioaugmented treatment. In addition, a decrease in PCP levels also correlated significantly with an increase in gene expression of PCP-degrading enzymes, pcpB (r = ?.77044) and TftD (r = ?.87905) (p < .05). PCP concentrations decreased and pcpB or TftD expressions were higher in bioaugmented treatments with S. chlorophenolicum (50%, 7-fold) or B. cepacia (67%, 10.7-fold), respectively, than indigenous treatment. Therefore, bioaugmentation with known PCP-degrading bacteria enhanced remediation of PCP-contaminated groundwater than indigenous bacteria alone. Results of this study may provide a more efficient and environmentally friendly technique for on-site remediation of PCP-contaminated groundwater.     

Phylogeny of Sphingomonas species that degrade pentachlorophenol

Four pentachlorophenol (PCP)-degrading bacteria isolated from geographically diverse areas have been examined in detail as regards their physiology and phylogeny. According to traditional biochemical methods, these strains had been classified as members of the genera Arthrobacter, Flavobacterium, Pseudomonas, and Sphingomonas. The PCP degradation pathway has been studied extensively in Sphingomonas (Flavobacterium) sp strain ATCC 39723 and the first three degradation steps catalyzed by a PCP-4-monooxygenase (PcpB) and a reductive dehalogenase (PcpC) that functions twice are well established. A fourth step appears to involve ring-fission of the aromatic nucleus (PcpA). Molecular analyses revealed that the PCP degradation pathway in these four strains was rather conserved, leading to a phylogenetic analysis using 16S rDNA. The results revealed a much closer phylogenetic relationship between these organisms than traditional classification indicated, placing them into the more recently established genus Sphingomonas where they may even represent a single species. With 16S rDNA analysis, many bacterial isolates involved in degradation of xenobiotic compounds that were previously classified into diverse genera have been reclassified into the genus Sphingomonas. Received 14 April 1999/ Accepted in revised form 20 July 1999     

The survival of the pentachlorophenol-degrading Rhodococcus chlorophenolicus PCP-1 and Flavobacterium sp. in natural soil

The survival of two different pentachlorophenol (PCP)-degrading bacteria were studied in natural soil. The PCP-degraders Rhodococcus chlorophenolicus and Flavobacterium sp., both able to mineralize PCP into CO₂ and chloride in axenic culture, were tested for the capacity to survive and degrade PCP in natural soil. These bacteria were immobilized on polyurethane (PUR) foam and introduced into natural peaty soil to give about 10⁹ cells g^-1 of soil (dry weight). R. chlorophenolicus induced PCP-degrading activity in soil remained detectable for 200 days whether or not a carbon source was added (distillery waste or wood chips). Electron microscopic investigation performed almost a year after inoculation, revealed the presence of R. chlorophenolicus-like cells in the PUR foam particles. PCP-degrading activity of Flavobacterium sp. declined within 60 days of burial in the soil without enhancing the PCP removal. R. chlorophenolicus degraded PCP in soil at a mean rate of 3.7 mg of PCP day^-1 kg^-1 of soil, which corresponds to ca. 5×10^-3 pg of PCP degraded per inoculated R. chlorophenolicus cell day^-1. The solvent extractable organic chlorine contents of the soil decreased stoichiometrically (>95%) with that of PCP indicating that PCP was essentially mineralized.Abbreviations ATCC American type culture collection - DSM Deutsche Sammlung für Mikroorganismen - DW distillery waste - EM electron microscopy - EOX extractable organic halogen - GC/ECD gas chromatograph/electron capture detector - GC/MS gas chromatograph/mass spectrometer - PCP pentachlorophenol - WC wood chips - d.wt. dry weight - w.wt. wet weight - d.s. dry soil - d.H₂O distilled water - PCA polychlorinated aromatics     

Evidence for Natural Horizontal Transfer of the pcpB Gene in the Evolution of Polychlorophenol-Degrading Sphingomonads

The chlorophenol degradation pathway in Sphingobium chlorophenolicum is initiated by the pcpB gene product, pentachlorophenol-4-monooxygenase. The distribution of the gene was studied in a phylogenetically diverse group of polychlorophenol-degrading bacteria isolated from contaminated groundwater in Kärkölä, Finland. All the sphingomonads isolated were shown to share pcpB gene homologs with 98.9 to 100% sequence identity. The gene product was expressed when the strains were induced by 2,3,4,6-tetrachlorophenol. A comparative analysis of the 16S rDNA and pcpB gene trees suggested that a recent horizontal transfer of the pcpB gene was involved in the evolution of the catabolic pathway in the Kärkölä sphingomonads. The full-length Kärkölä pcpB gene allele had approximately 70% identity with the three pcpB genes previously sequenced from sphingomonads. It was very closely related to the environmental clones obtained from chlorophenol-enriched soil samples (M. Beaulieu, V. Becaert, L. Deschenes, and R. Villemur, Microbiol. Ecol. 40:345-355, 2000). The gene was not present in polychlorophenol-degrading nonsphingomonads isolated from the Kärkölä source.     

Molecular genetics and evolutionary relationship of PCB-degrading bacteria

Biphenyl-utilizing soil bacteria are ubiquitously distributed in the natural environment. They cometabolize a variety of polychlorinated biphenyl (PCB) congeners to chlorobenzoic acids through a 2,3-dioxygenase pathway, or alternatively through a 3,4-dioxygenase system. Thebph genes coding for the metabolism of biphenyl have been cloned from several pseudomonads. The biochemistry and molecular genetics of PCB degradation are reviewed and discussed from the viewpoint of an evolutionary relationship.Abbreviations BP biphenyl - bph BP/PCB-degradative gene - 23DHBP 2,3-dihydroxybiphenyl - HPDA 2-hydroxy-6-oxo-6-phenylhexa 2,4-dienoic acid - KF707 P. pseudoalcaligenes strain KF707 - LB400 Pseudomonas sp. strain LB400 - PCB polychlorinated biphenyls - Q1 P. paucimobilis strain Q1tod; toluene catabolic gene     

Inulinase-hyperproducing strains of Kluyveromyces sp. isolated from aguamiel (Agave sap) and pulque

Summary Two strains of Kluyveromyces marxianus (A1 and A2) isolated from ‘aguamiel’ (agave sap) and one strain of K. lactis var. lactis (P7) isolated from ‘pulque’ (its fermented product), were studied to make a survey of inulinase production. The strains of K. marxianus A1 and A2 were the best producers of inulinase, giving up to 2.5 times more enzyme than the control hyperproducing strain K. marxianus CDBB-L-278, and showed lower catabolic repression than this. One strain isolated from pulque was identified as K. lactis var. lactis and was also an excellent inulinase producer, being the first strain of this species reported as such. These strains were very good inulinase producers and they had low susceptibility to catabolic repression probably because the source from which they were isolated was rich in sucrose and oligofructans. They can be used in the transformation of inulin to produce fructose and/or oligofructans.     

Localization of HCH catabolic genes (lin genes) in Sphingobium indicum B90A

The locations of hexachlorocyclohexane (HCH) catabolic (lin) genes were investigated in HCH degrading sphingomonad, Sphingobium indicum B90A (that was isolated from India). Southern blot analysis revealed the presence of linA1, linC, linDER and linX (linX1 and linX2) on the plasmid DNA in Sphingobium indicum B90A.     

Quorum Sensing,or How Bacteria “Talk” to Each Other

Reviewed are recent advances in studying the quorum-sensing systems, which regulate gene expression depending on population density. Low-molecular-weight acyl derivatives of L-homoserine lactone (N-AHL) freely diffuse through cell membranes and determine cell-to-cell communication in bacteria. The quorum-sensing systems have first been found to regulate bioluminescence in marine bacteria Photobacterium(Vibrio) fischeriand Vibrio harveyi. Such systems are widespread and control expression of genes for virulence factors, proteases, antibiotics, etc., in various Gram-negative bacteria, including plant, animal, and human pathogens. Quorum sensing is a prominent example of social behavior in bacteria, as signal exchange among individual cells allows the entire population to choose an optimal way of interaction with the environment and with higher organisms.     

<Emphasis Type="Italic">Bacillus subtilis</Emphasis> as a bioindicator for estimating pentachlorophenol toxicity and concentration

Pentachlorophenol (PCP) and its sodium salt (Na-PCP) are extremely toxic chemicals responsible for important soil and groundwater pollution, mainly caused by wastes from wood-treatment plants, because chlorinated phenols are widely used as wood preservatives. The methods most commonly used for routine analysis of pesticides such as PCP and Na-PCP are high-performance liquid chromatography (HPLC) and gas chromatography–mass spectroscopy (GC–MS). A variety of rapid biological screening tests using marine organisms, bioluminescent bacteria, and enzymes have also been reported. In this study, rapid biological screening analysis using Bacillus subtilis was developed, to assess the biodegradation of PCP and its by-products in liquid samples. An empirical model is proposed for spectrophotometric analysis of Na-PCP concentration after growth of Bacillus subtilis.     

A bacterium that inhibits the growth of Pfiesteria piscicida and other dinoflagellates

Toxic dinoflagellate blooms have increased in estuaries of the east coast of the United States in recent years, and the discovery of Pfiesteria piscicida has brought renewed attention to the problem of harmful algal blooms (HAB) in general. Many bacteria and viruses have been isolated that have algicidal or algistatic effects on phytoplankton, including HAB species. Twenty-two bacterial isolates from the Delaware Inland Bays were screened for algicidal activity. One isolate (Shewanella IRI-160) had a growth-inhibiting effect on all three dinoflagellate species tested, including P. piscicida (potentially toxic zoospores), Prorocentrum minimum, and Gyrodinium uncatenum. This bacterium did not have a negative effect on the growth of any of the other four common estuarine non-dinoflagellate species tested, and in fact had a slight stimulatory effect on a diatom, a prasinophyte, a cryptophyte, and a raphidophyte. Shewanella IRI-160 is the first non-microzooplankton example of a microbe with the ability to control and inhibit the growth of P. piscicida, suggesting that bacteria in the natural environment could play a role in controlling the growth and abundance of P. piscicida and other dinoflagellates. Such bacteria could also potentially be used as management tools to prevent the proliferation of potentially harmful dinoflagellates in estuaries and coastal waters.     

Occasional pathogenic bacteria promoting ice-ice disease in the carrageenan-producing red algae Kappaphycus alvarezii and Eucheuma denticulatum (Solieriaceae,Gigartinales, Rhodophyta)

The bacterial isolates from normal and diseased branches of Kappaphycus alvarezii and Eucheuma denticulatum in the Philippines were examined for possible role in the development of the ice-ice disease. The numbers of bacteria on and in ice-iced branches were 10–100 times greater than those from normal, healthy ones. Gram-positive bacteria predominated in almost all branch sources, but with an increasing proportion of agar-lysing bacteria in branches suffering from the ice-ice disease. These agar-lysing bacteria were composed of yellow and non-pigmented, spreading colonies identified to the Cytophaga-Flavobacterium complex and the Vibrio group. Among isolates which mainly appeared on ice-iced branches, two strains, designated as P11 (Vibrio sp.) and P25 (Cytophage sp.), which showed pathogenic activity, were obtained. These strains caused early ice-ice whitening of K. alvarezii especially when subjecting branches to environmental stress, such as reduced salinity and light intensity, suggesting that these bacteria were occasionally pathogenic. This paper offers new evidence of bacterial role in the development of so-called ice-ice disease among farmed species of Kappaphycus.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Presence of Quorum-Sensing-Mediated Gene Regulation in Pathogenic Ice-Nucleation-Active (INA) Bacteria

Nine out of a total of 20 pathogenic ice-nucleation-active bacteria, with different levels of inducible INA, were tested and found positive for their ability to synthesize quorum-sensing (QS) signals. The bacteria were isolated from willow plants and belonged to the genera Bacillus, Erwinia, Pseudomonas and Sphingomonas. As reporter bacteria, to detect the homoserine lactone (HSL) autoinducer, Agrobacterium tumefaciens, Chromobacterium violaceum, Pseudomonas aeroginosa, Aeromonas hydrophila and Vibrio fischeri strains were used. We thus provide evidence that pathogenic ice-nucleation bacteria with inducible INA produce QS signals that in other bacteria have been shown to be in the control of genes of importance for pathogenicity.     

Microbiological survey for selected bacterial pathogens in European storm petrel (<Emphasis Type="Italic">Hydrobates pelagicus</Emphasis>, Linnaeus 1758) from Grosa Island (Murcia,Southeastern Spain)

The current work shows the first step in the knowledge on the health status of European storm petrel (Hydrobates pelagicus) colony inhabiting Grosa Island (Murcia, SE Spain). We performed a screening about the bacterial pathogens carried by them (among the infectious agents checked, bacteria of the orders Mollicutes and Chlamydiales, and the genera Salmonella are of main interest) and compare these results with similar works performed in Larus species because most of the breeding colonies of storm petrel share habitats with gull colonies, and these could become pathogen reservoirs to petrels. Our results show the European storm petrels sampled have absence of pathogens of main interest and low levels of opportunistic pathogens. No Mycoplasma species were isolated, and no Chlamydophila psittaci were demonstrated by lipopolysaccharide antigen immunodetection. The commensal bacteria were isolated in higher frequencies than the previous [Staphylococcus epidermidis (5/15), Staphylococcus hominis (2/15) and Staphylococcus aureus (1/15)]. The rate of isolation of Gram-negative was lower than in the previous Gram-positive bacteria [Pasteurella sp. (1/15) and Pseudomonas aeruginosa (1/15)], and no Enterobacteriaceae were isolated. The absence of pathogen carriers on European storm petrel is the main conclusion of this survey; it is an evidence that the bacterial infectious pathogens described in gulls may not be an important selective force on their survival.     

Origin and formation of the Spanish Imperial Eagle ( Aquila adalberti )

A review of the paleontological records of the Eastern Imperial Eagle (Aquila heliaca) and the Spanish Imperial Eagle (Aquila adalberti) in the context of the paleoecological environment in Eurasia during the Pleistocene and Holocene epochs is presented. The Eastern Imperial Eagle expanded its range in Eurasia during the last Pleistocenic glaciation favoured by the expansion of the steppes. The first records of Spanish Imperial Eagles are from the Late Pleistocene and Early Holocene in the eastern Iberian Peninsula, and their distribution seems to have been limited to the distribution areas of Mediterranean vegetation and the European rabbit. Individuals of migrant A. heliaca could have reached the Iberian Peninsula at the end of the Pleistocene–beginning of the Holocene. These individuals could have adapted to the Mediterranean ecosystem, subsequently specializing in a diet of rabbit, a prey which is in abundance all year round. Due to the availability of such prey, A. heliaca would become more sedentary. These individuals may have overcome their breeding phenology and paired up assortatively, becoming genetically separate from the migrant populations and initiating the speciation mechanisms for sympatry or parapatry that resulted in A. adalberti. This is one possible mechanism. These findings reported here support the recent age of divergence between both taxons, and the incipient speciation supports its taxonomical considerations as a semi-species. The study reported here complies with the current laws of Spain.